


What Can Be Fixed

by lettucepunch



Category: Big Hero 6 (2014)
Genre: Aged-Up Hiro, Alternate Universe - Time Travel, Angst, Brother Feels, Emotional Hurt/Comfort, Hurt/Comfort, Older Hiro, Tadashi Lives, Time Travel, Time Travel Fix-It
Language: English
Status: In-Progress
Published: 2016-06-02
Updated: 2016-06-13
Packaged: 2018-07-11 19:09:20
Rating: General Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 6
Words: 8,777
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/7066483
Author URL: https://archiveofourown.org/users/lettucepunch/pseuds/lettucepunch
Summary: <blockquote class="userstuff">
              <p>Ten years after Tadashi's death, Hiro finds himself back before the accident. He couldn't stop Tadashi from going in a burning building the first time around. This time, he won't fail.</p>
            </blockquote>





	1. Start

**Author's Note:**

  * Inspired by [BH6 Time Portal AU](https://archiveofourown.org/external_works/203248) by non-fatmilk. 



> Hey guys, hope you enjoy my first attempt at fic writing. (o _ o;;) This doesn't really have a specified number of chapters, nor does it have a specified release schedule. Pretty much goes up whenever I write more. (e _ e;;;;;;;) This chapter is pretty short, but just bare with me.

A blinding flash of green light is the last thing he sees before he blacks out. 

When he wakes back up, he sees that he is in the end of some dark alleyway, the bright lights of the bustling city several yards away. He looks down and sees that thankfully, his armor suit is still intact. He taps the side of his helmet and the screen inside lights up. Where the clock should be, it simply reads “ERROR”. Great. At least he knows it’s night, from the stars above. He stands, and feels pain shooting through his entire body. _Why am I so sore? What happened?_ , he wonders. The young man takes a deep breath, then begins walking towards the busy street. Just a few feet away from the entrance to the alley, he stops. Across the street he sees the impossible. His 14 year old self, chatting happily with a man he hadn’t seen in 10 years. A dead man. His brother. Tadashi.

Hiro feels his heart rate and breath speeding up. He struggles to gain control over himself as he begins to shake too much to stand straight, leaning heavily against the wall of the alley. He slides down to the ground and puts his head in his hands, eyes watering, as his breath gets more and more ragged. Hiro racks his brain for how his younger self could be there with Tadashi. There are no answers. He begins hyperventilating and the inside of his helmet fogs up slightly. He takes off the helmet. 

“Hey man, you alright?” A voice out of nowhere.

Hiro becomes aware of a young man crouching in front of him. “Are you having a panic attack? My friend gets those sometimes. Breath with me, okay?” The young man places a hand on Hiro’s shoulder and begins breathing slow and deep, giving Hiro’s shoulder a gentle pressure with each breath out. He slowly begins to slow his breathing, until it is more or less normal (besides an occasional hiccup). The young man asks if he’s going to be okay, and Hiro reassures the man, who gives Hiro a water bottle from his bag, then leaves. 

Digging around in his pockets, Hiro finds a few 20 dollar bills, exits the alley, and purchases a plain backpack and cap. He hastily stuffs his armor into the bag, then pulls the cap over his hair, low over his eyes. Hiro takes another deep breath, then begins walking to his aunt’s cafe. 

\------------------------------------------------------------------------------

Even with the cafe closed and the lights out, Hiro can still peer through the windows. Immediately he notices the decor. The cafe had been refurbished three years ago, so why did everything look the same as it had before Tadashi died? Hiro feels his stomach churning, and just wants this to be a bad dream. However, the pain he felt earlier hasn’t gone away, just dulled, and he knows that this is real. A word flashes in his mind, along with a new wave of pain. 

_Time travel._

What? There was no way. And yet. His broken clock. Tadashi alive, with a teenaged Hiro. The aged cafe interior. His heart begins to speed up again and he knows he has to get away from here. 

\------------------------------------------------------------------------------

He finds himself at the entrance to the SFIT student lab building before he even knows it’s where he wants to go. Hiro pulls his gauntlet out from his backpack, opens it up, and connects some wires to the electronic lock of the building, and two minutes later he’s disabled all security systems and is letting himself in. The 24 year old quickly finds his way to his brother’s/his old lab, and finally breathes easier when he sees a familiar red and white case sitting by the wall.

“Ow,” he practically whines, barely able to wait for the robot to activate and inflate. 

“Hello. I am Baymax, your personal healthcare companion. On a scale from 1 to 10, how would you rate your pain?” Baymax’s voice soothes Hiro, who begins shaking out of relief rather than fear. 

“Um. 4? Maybe 5?” Hiro’s voice trembles, hoping that the robot recognizes him, and he’s just been hallucinating his own dead brother. He hears a soft whir as Baymax quickly scans him. 

“My scans show: dehydration and raised adrenaline levels, resulting in a headache and an elevated heart rate. Additionally, you show signs of sleep deprivation and hunger.”

Hiro sighs in relief, deciding he just needs a good night’s sleep and more fluids, before freezing. This was no longer his lab. Baymax should not be here. He looks around, and realizes that Tadashi’s things are still there. Hiro begins to hyperventilate as Baymax continues talking.

“My scans also indicate a discrepancy in my patient files. The Hiro Hamada I scanned before is a 14 year old boy, yet you, Hiro Hamada, are 10 years older. My self-diagnosis shows no errors in my programming. I do not understand,” Baymax states, as he walks up to Hiro, embraces him, and begins to alternate between slightly inflating and deflating, to show Hiro the correct speed to breathe. Hiro shudders, but still tries to stay on beat with Baymax.

“I-I-I th-think I t-time traveled,” he stutters, “b-but I don’t know why, or h-how.”

“New patient file created: Hiro Hamada elder.”

\------------------------------------------------------------------------------

Sufficiently calmer now, Hiro paces back and forth slowly in Tadashi’s lab. He has recalibrated his helmet’s clock to match the current time, and notices that the SFIT Showcase is only two weeks away. He has to decide what to do about Callaghan, and fast. There is no way to know when Callaghan set the bombs, whether it be today, the day of the Showcase, or even just before the explosion. All Hiro knows is that he has to save Tadashi. Should he try to talk to the professor beforehand, or try to prevent the explosion, or just save his brother, professor be damned?

At any rate, he needed to come up with a plan. But first, he needed to leave the lab. Seeing the sky begin to lighten, Hiro gathers his few belongings, hugs Baymax, and quietly exits the building before any students or professors arrive. As Hiro puts on his cap and walks down the street away from the school, he fails to notice a young man wearing a well-worn green blazer and beat-up cap watching him leave the labs, peering around the corner of the building with his moped.


	2. Hit and Run

**Summary for the Chapter:**

> Tadashi can't stop thinking about the stranger.

**Notes for the Chapter:**

> Another short chapter (o _ o;;;) Eventually I'll put out longer ones, but for now, this is all you get ;^)

Tadashi parks his moped, takes off his helmet, and walks to the door of the building. He takes out his student ID, goes to swipe it, but is confused to find that the lock is not reacting to his card. He tugs gently on the door handle, and makes a weird face when it opens. Tadashi peers into the building cautiously, and seeing no one, he enters and walks to his lab. Just like the front entrance, the door to his lab is strangely unlocked, and Tadashi notices that the small green light on the lock, which is usually lit, is now dark. Well. Tadashi resolves to call security, and as he’s telling them about the nonfunctional security systems (leaving out the stranger he’d seen before), he notices that Baymax’s battery is lower than it should be after charging all night. He sighs and makes a mental note of it before seeing that his stool has moved from its usual spot next Baymax’s charging station. 

Tadashi rolls the stool back to its spot, thinking about the stranger he saw outside. The man had had a familiar slouch and an even more familiar mess of hair, yet Tadashi pushes images of Hiro out of his mind. The man was definitely not a 14 year old. He was around Tadashi’s height, but was less broad in his shoulders. But even with his lean figure, the man still clearly had some muscle to him. Tadashi wonders what the man was doing at SFIT so early in the morning (though he's not one to talk), and who he was (Tadashi knew every student who worked in the building). Still, as he sits down to take a look at Baymax’s charging station, he can’t get the stranger’s resemblance to Hiro out of his head. 

\------------------------------------------------------------------------------

Tadashi looks up from his robot as the alarm on his phone goes off. Time for his first class of the day. By now, Hiro should be waking up and getting ready for another long day of making microbots. Tadashi grabs a granola bar from the box on his desk, then heads out to the lecture hall. He runs into Gogo and Honey Lemon on the way, the former patiently listening to the latter’s excited rambling. She’s talking about the morning’s possible “security breach” of the labs, and how an email sent out by administration said to check that all belongings and equipment can be accounted for. 

“Everything fine with your stuff? Baymax is pretty valuable tech,” Gogo interrupts Honey Lemon to ask Tadashi. 

“Yeah, everything’s fine. I’ve been in the lab all morning, anyways,” Tadashi says while smiling reassuringly. As Honey Lemon begins talking again, Tadashi’s mind returns to the stranger. The man had seemed like he was in pain as he walked away, and Tadashi’s heart surges as he once again thinks of his baby brother, this time in the same pain that the stranger bore. He resolves to actually talk to the stranger if he sees the man again, and maybe invite him in for treatment. 

\------------------------------------------------------------------------------

After all his classes are finished, Tadashi goes back to his lab to grab a textbook and some notes before going home. Before he leaves for the night, however, he makes sure that his door is securely locked. Tadashi goes home to his aunt and brother.

\------------------------------------------------------------------------------

After dinner, Tadashi sits on his bed, going over his notes and checking his answers studiously. On the other side of the bedroom, a teen fiddles with his latest invention. Tadashi looks up from his work to just stare at the youth. _Yeah. That guy totally looks like Hiro_ , he thinks. Hiro realizes that the sound of pen moving across paper has stopped and turns around.  
“Bro? What’s up?”

“Hmm? No…” Tadashi is jolted from his train of thought. He considers telling Hiro about the stranger, but decides against it. Instead, Tadashi shares the news about the security system. “I got to SFIT today and the security system for the entire lab building was out. Cameras out, everything unlocked, but nothing was missing.”

“Huh,” Hiro turns around, already losing interest. “That couldn’t be that hard. I could probably do that from here if I really wanted to.”

Tadashi sighs, then puts his book and papers on the bedside table. He reaches over to turn out the lamp, and tells Hiro to do the same. The two brothers drift peacefully off to sleep at the same time.

Meanwhile, curled up in a questionably clean bed at the end of his second day, Hiro begins to cry, thinking about his brother’s happy face . Coming to terms with the fact that he really did time travel was difficult, but he forces himself to ignore his inner voice saying that it couldn't be possible. He struggles to clear his mind, definitely not thinking about the cheap, seedy motel he was currently staying in. Hiro knows he’s nearly out of cash now. His stomach growls, remembering that he hasn't eaten in over 24 hours, and it’s beginning to show as exhaustion and hunger begin to cloud his mind. Hiro passes out, whimpering and dreaming of an imaginary Tadashi making him breakfast. 

\------------------------------------------------------------------------------

The next morning, Hiro slinks out of the motel, still feeling an aching pain throughout his body. He suspects the pain is partially caused by his dehydration and hunger, and so uses the last of his money to purchase a plain bagel and a water bottle. He walks for a couple minutes to sit at a bench in a small park, then weighs his options. The bottle can be refilled at any of the abundant hydration stations around the city. The bagel, however, can not. For now, though, he decides to split the bagel into thirds, then puts two-thirds of it into his bag with his armor. Despite his hunger, Hiro forces himself to eat slowly, taking small bites to make the meal last longer. When he is (unfortunately) done with his third, he downs the entire bottle of water, then walks to the park’s drinking fountain to refill it. Little does he know, he is being watched.

On the other side of the street, Tadashi stops dead in his tracks as he recognizes the man in the park. He watches as the man gets up to get more water, and can tell that the stranger still seems to be in pain. Tadashi bites his lip in thought, then crosses the street towards the stranger.

Hiro sits once more on the bench, looking blankly at the ground. He hears approaching footsteps, but ignores them. Then, they’re in front of him.

“Excuse me, sir?”

An all too familiar voice fills Hiro’s ears and he feels his breath catch in his throat. Not daring to lift his head all the way, he looks at the voice’s shoes, and knows. Tadashi. Hiro would know those sneakers anywhere. He can feel another panic attack coming on, as his heart begins to beat faster. 

“Sir? Are you okay? Did I startle you?..... Are you having an attack? Sir?”

Hiro makes a decision. Keeping his face down so as to not be recognized, he punches Tadashi in the stomach, just hard enough to push him back a bit but not enough to make him fall over. With his newfound space, Hiro makes a run for it, still making his best effort to hide his face, leaving Tadashi behind, confused and bent over.

_Sorry, Tadashi. I’ll make it up to you, somehow._


	3. Impossibilities

**Summary for the Chapter:**

> Tadashi contemplates the identity of the stranger, and questions what is possible.

**Notes for the Chapter:**

> This chapter's a little longer today and focuses mostly on Tadashi ♥♥♥♥♥

Tadashi moves himself carefully onto the bench to recover. _What the hell_. Tadashi is unsure whether the man was crazy, or just lashing out because of his distress. He also couldn’t decide if it was his fault, since he did, after all, approach suddenly and for no real reason. _Maybe he has PTSD_ , Tadashi wonders. _He seemed old enough to maybe have some military experience. Or maybe it’s just severe anxiety._ Whatever it was, Tadashi was certainly not making the mistake of approaching the man like that again. Next time (did he think there would really be a next time?) he would be more careful and give the man space, and speak a little more gently. Even though the stranger had physically assaulted him, Tadashi Hamada still wants to help. He stands up. 

\------------------------------------------------------------------------------

Hiro curls up in an alleyway, already feeling like _shit_ for hitting Tadashi. His big brother. Or rather, younger big brother. Hiro chuckles scornfully, considering his current circumstances. He’s 24 and yet he’s moping in some dark corner because he hit his brother, who, to Hiro, had been dead for 10 years. Then, he has a thought. How did he time travel in the first place? Then, pain. Trying to remember brings about a newer, more intense wave of pain to his body, and Hiro grabs his head, whimpering as he curls in on himself. Through the pain, he is unaware of the footsteps approaching, quickening in pace. Hiro barely registers strong hands on his shoulders before he passes out.

\------------------------------------------------------------------------------

Tadashi is glad the stranger hadn’t hit him too hard, as the pain had already subsided. He suspects the man had purposefully held back, not wanting to injure Tadashi seriously. He also suspects that despite his appearance, the man is quite strong, and is capable of some damage. Tadashi sighs, then begins to jog in the direction that the man went in, not wanting to leave someone in need by themselves. 

It’s not long before Tadashi finds what he’s looking for. He doesn’t see the man at first, but hears sounds of pain coming from the depths of an alley as he passes it. He does a double take, finally spotting the man, immediately knowing that something is wrong. 

”Hey! Sir? …..Alright. Come on, man,” Tadashi exclaims as he forces himself to be calm. For the sake of the patient. He pulls the stranger to his feet, then pulls the man’s arm over his own shoulders. Luckily, SFIT is not far off, and he begins the slow walk to school, supporting his new patient all the way. 

\------------------------------------------------------------------------------

When Hiro opens his eyes, he finds himself staring at a ceiling, rather than the sky he was expecting from the alley. He notices a blanket draped over him, as he lays on top of another blanket on the floor of a very familiar lab. _No. No way._ Despite his best efforts to avoid his brother, Tadashi had still managed to find him and drag him back here. Hiro’s only hope was that he had changed enough in the last 10 years that he could can convince Tadashi that he just happens to look like the student’s younger brother by complete and utter coincidence.

 _There’s no way he’s going to believe me_. 

Hiro slowly sits up, and immediately sees Tadashi sitting near his feet, legs crossed, and his back turned to Hiro. Hiro swallows nervously.

“Um. Uh,” Hiro stutters, unsure of what to say. Tadashi slowly turns around to face him. Hiro feels his heart leap into his throat at the sight of his brother, alive and real. 

”Thank goodness you're alright. I found you in an alley unconscious. You’ve been out for about an hour,” Tadashi speaks with a tentative smile. “Sorry if I startled you earlier.”

“Um. Th-thanks. For picking me up. Uh. I'm sorry. For hitting you.”

Tadashi smiles, a little less worried about Hiro. “It's alright. You didn't even leave a bruise,” _though you could have if you really tried_. Both men think it, but neither say it. Tadashi gets up, grabs an unopened water bottle from the case under his desk, a couple of granola bars from his stash, and a bottle of painkillers, handing it all to Hiro.

“Take two with some water. And eat those. I can also go get something for you from the cafeteria, if you want,” Tadashi says, gentle and firm. Hiro flinches, remembering his dream from the night before. And yet, he knows that he can’t stay, and he definitely can’t get caught again. He wants nothing more than to hug his brother and never let go, but he has to go.

“Uh, I guess? Maybe just a sandwich or something?” Hiro asks, swallowing a couple of pills. He really is hungry, and a sandwich sounds great right about now, but this could be his only chance to get away before Tadashi asks about his identity. Tadashi smiles widely now, tells him to stay put, then dashes out of the room. Hiro swallows nervously, then rises to his feet. He looks around quickly, seeing his backpack by the door. Taking a few more granola bars and another water bottle, he stuffs them into his backpack. Standing in the door, he looks back one more time and spots the two blankets on the ground. After a second of thought, he quickly grabs one before leaving the lab, pulling his hat low over his face again. At the main entrance of the building, he pushes past a large, dark man with a faded green sweater, and a tall, thin woman dressed in bright oranges and yellows. They glance at Hiro briefly, then enter the building. 

\------------------------------------------------------------------------------

When Tadashi returns to his lab with lunch and sees the open door and empty room, he slaps his free hand to his forehead, groaning. _Should have known he would run. Man, I should have brought him with me!,_ he thinks. 

“What’s wrong?” A soft, high-pitched voice comes from behind him in the hallway. Tadashi turns to see Honey Lemon and Wasabi looking at him with mild concern.

“Did you two see a guy you’ve never seen before leaving?” Tadashi inquires. Honey and Wasabi look at each other. 

“Yeah, actually. There was a skinny guy with a baseball cap and backpack who just left as we arrived,” Wasabi speaks up. Tadashi sighs, turning and walking back into the room with his hand over his eyes. Out of the corner of his eye, he sees that there is one less blanket on the floor. _Well, at least he won’t freeze,_ Tadashi thinks to himself. 

“Who was he? You seem pretty disappointed that he’s gone,” Honey asks. 

“I picked him up off the street,” Tadashi replies. His friends give him a look and he knows they’re thinking something inappropriate. “Not like _that_ , I mean picked him up as a patient! He passed out, so I brought him here because of Baymax.” Tadashi ignores his friends’ looks of disappointment. “He seemed hungry and dehydrated, and according to Baymax, I was right. I stepped out to grab something to eat, and it looks like he ran for it.” 

“Did he tell you his name? Maybe someone around here knows him.” Tadashi hesitates before telling her that the stranger hadn’t said a lot, much less his name. His friends look dissatisfied, the mystery unsolved, but they go back to their own lab areas, needing to do more work on their projects. When they’re gone, Tadashi closes the door, sits on his stool, and rubs his temples. He thinks back to what happened when he brought the man into the lab.

\------------------------------------------------------------------------------

When Tadashi arrived at SFIT, the student lab building was mostly empty. He nodded to the few other students in the building who greeted him as he walked in with the stranger’s arm draped around Tadashi’s shoulders. He hurried to his lab, and anyone who happened to be in the way moved out of the way quickly. Tadashi unlocked his door, grabs one of the blankets folded in the corner, stashed away for his late nights, then layed it flat on the floor. He carefully lowered the surprisingly light man onto it, then went back and grabbed one more blanket to cover the man with. 

“Ow,” Tadashi said softly to the robot, not wanting to disturb the man. Baymax inflated, and looked at Tadashi. 

“Hello. My name is Baymax, your personal healthcare companion. How can I help, Tadashi?” The robot inquired. 

“Baymax, scan this man. He passed out in the street, so make sure he’s not sick or anything.” 

Baymax turned to the man lying on the floor, then began the scan, while Tadashi watched the robot carefully, hoping to at least see how Baymax performed with real patients. 

“Scan complete. The patient, Hiro Hamada, suffers from dehydration, hunger, sleep deprivation, and an elevated heart rate which is steadily returning to normal levels. Additionally, he seems to be suffering from delayed muscle onset soreness and migraines, causing pain throughout his body,” the robot stated. Tadashi turned away from Baymax to face his patient. _Shit. Even from the front, he looks like Hiro._

“Hm…..Wait. What?” Tadashi took a few seconds to register what Baymax said. Hiro Hamada? That couldn’t be possible. Maybe Baymax didn’t work properly. “What did you say his name was?” 

“My patient’s name is Hiro Hamada. He was here two nights ago for treatment, and I gave him the same diagnosis, which he has ignored. I would recommend the patient drink plenty of water, have a balanced meal, and plenty of rest.” 

Tadashi put his head in his hands. Why was there always an issue with Baymax? Wait. Two nights ago was when the security system was shut down inexplicably. _Don’t tell me that guy came here and messed with Baymax somehow…?_

“Baymax, play footage of the patient the first time you saw him the other night,” Tadashi commanded. He watched intently as Baymax’s chest lit up.

As video-Baymax activated, the man’s face comes into view. He was sweating, cheeks tinged slightly red, eyes wide. He looked terrified and rushed. Tadashi stared as Baymax identifies the man as Hiro Hamada, then points out the age discrepancy in his medical record of Tadashi’s brother. The man stutters as he talks about time travel. Tadashi watched for a while longer, seeing the man calm down slowly. 

“Baymax, fast forward to when he leaves.” The video cut to the man looking at Baymax with a pained expression, hugging the robot, then leaving the lab and closing the door behind him. Fast forward. A few minutes later, Tadashi enters and moves a stool, then Baymax’s chest screen turned off. 

Tadashi closed his eyes and let out a long breath, then looked back at the man’s face. He leaned over, and gently removed the man’s hat. Tadashi’s breath caught in his throat when the man’s mess of dark hair completed his resemblance to Tadashi’s baby brother. 

“Baymax, are they really the same person?” Tadashi hoped that the robot would say no, but his face fell when Baymax confirmed the identity of this stranger. 

\------------------------------------------------------------------------------

Rubbing his face with his hands, Tadashi looks back at where the man had been 15 minutes before. He can’t get the man’s look of distress in the video out of his mind. He’d managed to keep it together when the man woke up, but he still didn’t understand. Time travel? How was that even possible? And yet, Tadashi can’t forget the man’s eyes. The same eyes that he’s been looking at for the last 14 years, on the face of his little brother. _Shit._ So what now? 

Tadashi sighs and decides to trust the impossible. Every instinct he has in his body was telling him to protect the man, no matter how irrational it might sound. Next time he saw the man, there was no way Tadashi was letting him go until he had answers. 

Tadashi didn’t see the man again until the day of the SFIT Showcase. 


	4. Thinking of You

**Summary for the Chapter:**

> The Hamada brothers always keep each other in their thoughts.

Hiro stops running when he can no longer hear an imaginary and disappointed Tadashi asking why Hiro left, when he was specifically told to stay put. Looking around, Hiro finds that he’s across town from SFIT, in the sketchy part of the city. In fact, he’s in front of the warehouse that Callaghan had used as a base to produce microbots. Hiro feels a surge of anger, remembering the professor’s crimes. He’s tempted to destroy the warehouse before it can even be used, but stops himself. _Don’t cause trouble, Hiro. How will you explain who you are if you get caught?,_ Tadashi reasons. Still shaken from the close encounter with his brother, Hiro just slumps against the side of the warehouse in the shade. He’s calmed down a considerable amount, but it seems that running so far has just exacerbated his sore muscles. 

Hiro pulls a water bottle out of his backpack and drinks half of it. Then, he begins planning what to do next. 

\------------------------------------------------------------------------------

Hiro spends the next two weeks leading up to the Showcase stalking people. He sneaks around Lucky Cat Cafe and the brothers’ garage, checking on their progress with the microbots. A week later and his younger counterpart has finally finished calibrating the neurotransmitter. Tadashi and the younger Hiro run tests to make sure that the bots work, as the older Hiro watches from across the street, outside of the light of the streetlamps. Seeing the microbots rise in a wall above Tadashi’s head nearly sends Hiro into another panic attack, but he is able to push it away, seeing the look of joy on both brothers. Hiro reminds himself that his invention had been meant for good; its innocence was corrupted by Callaghan’s need for vengeance. 

Hiro doesn’t limit himself to just stalking himself and his brother, though. He sneaks around SFIT, hat pulled low, watching Callaghan’s movements. Hiro is surprised at how different the professor was from “Yokai”. Before the fire, Callaghan was a kind professor who seemed to always be ready to help and challenge his students. But afterwards. As Yokai, Callaghan had become a ruthless man, intent on completely _destroying_ Alistair Krei for the loss of his daughter. And while Hiro admits to sympathizing with Callaghan’s anger and grief, he can’t help but hate the professor. He alone is responsible for Tadashi’s death and all of Hiro’s grief, depression, and anxiety. Callaghan might not have meant for Tadashi to die, but it was still his crime. 

And now, Hiro has his chance. He knows that he can save Tadashi, Abigail, and Baymax. He doesn’t have to lose anything anymore. _But then what?,_ Hiro wonders. He doesn’t know how he arrived in the past, and there’s no way he knows how to return to his own time to enjoy the fruits of his labor. Even if he’s able to save Tadashi, Hiro still can’t do anything here. To Tadashi, this Hiro is just some crazy guy who assaulted him, and keeps running away. Hiro knows that the only way he can reunite with his brother is by going back to his own time, and there’s no guarantee of that happening. That doesn’t mean he won’t try. Hiro will do anything to save Tadashi. He has to. 

\------------------------------------------------------------------------------

Tadashi laughs alongside a teenage Hiro as they make silly shapes out of the microbots. There’s nothing that can ruin their joy in this moment; the microbots work and that’s all that matters. Tadashi looks from the bots to his brother’s face and feels pride and love rise in him. His happy little genius baby brother. There was no way that Hiro could fail. He would take the SFIT Showcase by storm and blow everyone away with his tech. 

Later that night, Tadashi lays in bed thinking. Hiro is already fast asleep on the other side of the room. Tadashi can see his small frame practically drowning in blankets and smiles. Then, he remembers the pained and terrified face of the man from a week ago. He hadn’t seen the man since, and was becoming increasingly worried. Tadashi had noticed that the older Hiro was wearing the same clothes both times they crossed paths, though the instances were a couple days apart. Knowing Hiro, he probably didn’t have much of a plan and was just wandering the streets at night with only a thin stolen blanket. Or worse, bot fighting for money. Tadashi shudders at the thought of it, then stifles a laugh at himself. Worrying about a grown man with some obvious strength in his lean figure. Judging from when he carried Hiro to SFIT, Tadashi guesses that his brother was a couple inches taller than him. But to Tadashi, Hiro’s expression makes him seem so much younger and smaller than he is. His expression. Tadashi frowns. 

What had happened in the last 10 years of the older Hiro’s life that changed him from a happy, bright, young teen into such a nervous, damaged man? Why did Hiro keep running from Tadashi? Could he no longer trust his own older brother in the future? Tadashi only hopes that he gets the chance to speak with the 24 year old again. _24?_ Tadashi recalls the medical record he saw in Baymax’s files. _So he's older than me,_ Tadashi thinks. _Not my little brother anymore, huh?_ The two faces of his brother dance in front of him as he drifts off to sleep. 

\------------------------------------------------------------------------------

 _Tadashi?_ The familiar voice of a teenage genius rings out in the darkness. Tadashi looks around, searching and straining his eyes. Suddenly, the teen is in front of him. Hiro smiles widely, the gap in his front teeth showing. Tadashi grins and reaches out to ruffle his brother’s hair, and Hiro’s happy expression turns to one of pure fear, eyes going wide and smile disappearing. A wave of microbots rises from seemingly out of nowhere and swallow Hiro in darkness, while Tadashi shields his head with his arms. When he looks up, Hiro is gone. 

_Hiro?! Where are you?_ Tadashi yells out frantically. 

_Tadashi?_ Tadashi spins around to meet the deeper and more timid, yet still somewhat familiar, voice of his future brother. Tadashi flinches when he sees a broken, bruised, and bloody man standing there. Tadashi rushes forward and grabs Hiro by the shoulders. Hiro doesn't react to his brother’s panic.

 _Hiro, what happened to you?!_ Tadashi asks, distraught. 

_What happened to me?_ Hiro changes from frightened to angry in a split second. _You happened to me! You did this!_

Hiro knocks Tadashi away, and Tadashi falls to the ground. A bleeding Hiro looms over him with a huge wave of microbots. As the microbots crash over Tadashi, absorbing him in a robotic ocean, he hears more voices.

 _How could you, Tadashi? You were supposed to protect him...How could you? How could you, Tadashi?_ Tadashi hears the disappointed voices of his parents, as they repeatedly scold his failure. The disapproving and angry eyes of his family are the last thing he sees before being swallowed by darkness.

Tadashi wakes with a jolt. Sweating, he stares past the open divider of the bedroom. He lets out a sigh of relief when he sees Hiro safely and soundly sleeping in his bed. Laying back down, Tadashi slips back into an uneasy slumber. 

\------------------------------------------------------------------------------

The morning before the Showcase, Tadashi can’t give an honest answer to his family’s questions.

In the week following his nightmare, Tadashi often slips out to visit his lab at SFIT in the middle of the night, in hopes that the future Hiro has returned for either treatment, food, or water. Every time, he is disappointed to see only his robot in the room, and no sign of his nervous brother having been there. His moonlight escapades are beginning to show in the deepening bags under his eyes. 

“You okay, bro? You look pretty tired,” Hiro asks the morning before the Showcase. 

“Are you sleeping alright, sweetie?” Cass asks, putting a plate of waffles in front of Tadashi. She slides a mug of coffee over to him, concern showing on her face.

“I’m fine, don’t worry about me. Shouldn’t you be more worried about the Showcase tomorrow?” Tadashi reassures his family, thanking Cass for the meal and picking up a fork. She and Hiro don’t look any less worried about him. He sighs and says “Really, I’m fine, okay? I’ve just been a little more busy than usual.”

\------------------------------------------------------------------------------

The morning before the Showcase, Hiro sneaks into the SFIT Exhibition Hall. 

In the week leading up to the Showcase, Hiro often slips into the back of some of the various lectures Professor Callaghan gives. He keeps both Tadashi and Callaghan in his sights. He also scopes out the Exhibition Hall, under the pretense of helping with preparations for the Showcase. He finds that volunteering like this is pretty great for his current lifestyle. They give volunteers lunch and water, and on his breaks, he finds all the ways he can sneak inside without being seen. At night, Hiro hacks the security systems, making cameras loop footage of an empty hall, and doors unlock. He keeps watch for Callaghan, just in case the professor tries anything at night when no one is in the building. 

When Hiro is not attending lectures or working in the Exhibition Hall, he sleeps. He dreams of Tadashi taking him up in his arms, just like he’d done before the fire. Tadashi smothering Hiro with love and wiping away his fears. Tadashi smiling at Hiro and ruffling his hair, teasing the younger brother’s height and giving him a sugar-free lollipop. Tadashi talking about how proud he was of Hiro at the Showcase. Tadashi seeing the burning Exhibition Hall with panicked eyes. Tadashi running into the building and leaving Hiro behind. An explosion. Hiro always wakes up as his happy memories turn south, and Aunt Cass and his friends blame him for Tadashi’s death. 10 years ago, Hiro couldn’t do anything. Now, he can do something. For Tadashi, he will do anything. 

\------------------------------------------------------------------------------

The morning of the Showcase, Hiro and Tadashi sit in their garage with their friends. 

“Aw man, I’m so hyped for the Showcase! Maybe this year will finally be the year someone can make me breathe fire or something,” Fred talks excitedly. Gogo pops her gum, unimpressed while Tadashi raises an eyebrow and Hiro stifles a laugh. Wasabi groans and Honey just smiles apologetically. 

“Really, Fred, turning you into a dragon isn’t-” 

“Real science, yeah. You just keep on being a skeptic. Just wait until I’m stomping around the city with huge claws and breathing fire everywhere!” Fred cuts Honey off as she tries to correct him. 

“Ugh. Just. Just stop,” Wasabi says, putting his hand to his face. 

“Pizza’s here!” Cass’s voice calls out from inside the house. “You kids better eat and then get going!” 

Fred cheers, and the entire gang head inside. They enjoy their lunch together, then go back to garage to start taking Hiro’s tech to SFIT. Before they leave, Tadashi and Hiro look at each other. Tadashi, seeing Hiro’s nerves, is again reminded of his brother’s older counterpart and his dream. He makes up his mind to not think about the damaged man for the rest of the day. Tadashi puts a hand on his little brother’s thin shoulder, and Hiro takes a deep breath. 

“What if it doesn’t work? What if they don’t like it?” Hiro whines softly. Tadashi feels a twinge in his heart at the teen’s anxiety. 

“Don’t worry. Just breath and everything will be fine.” 

Later, Tadashi regrets these words. Oh, how he was wrong. 

**Notes for the Chapter:**

> And that's all you get for now! I hope you're having as much fun reading as I am writing :^)


	5. Burning

**Summary for the Chapter:**

> The day of the SFIT Showcase finally arrives.

Hiro’s presentation at the Showcase is just as big of a hit as they expected. Hiro is amazed when both Krei and Callaghan come to personally compliment his tech. Tadashi watches with a proud smile like the mother hen he is. Then, everything goes wrong.

Even under the watchful eyes of a 24 year old time traveler, Callaghan still somehow manages to light up the Exhibition Hall. _On the plus side,_ Hiro thinks, _it seems like he set up the explosion separately from the fire_. Hiro puts his armor suit on near the end of the Showcase, remembering that the fire alarms had gone off 10 minutes after it was over. 

_3...2...1._ Hiro counts down, standing in a dark hallway near the stage. Right when he expects it, the alarms begin to go off. The stragglers left behind in the Hall run outside, and Hiro knows he has to get to the front entrance in time to stop Tadashi outside. Then, he sees Callaghan. The man is walking towards the stage. Hiro pauses. _I could stop him, right now. Before he even gets the neurotransmitter._ Then, Hiro hears footsteps coming from the entrance. _No_. 

Tadashi had already entered the building. Hiro was too late. 

“Professor?...Professor Callaghan!”

Hiro can hear the confusion in Tadashi’s voice as both brothers watch Callaghan pick up the neurotransmitter and put it on. Callaghan turns around at the sound of his favorite student. Just then, Hiro jumps out of the hallway and punches Callaghan, knocking the neurotransmitter off the man’s head. They both scramble to get it, while Tadashi watches in shock. Callaghan gets there first, and pushes Hiro away with a wall of microbots. Hiro lands a couple feet in front of Tadashi, stunned. Callaghan stays for a second, then runs for it. 

Tadashi helps Hiro to his feet. Hiro responds by jumping away from Tadashi.

 _No no no no no no no can’t let him find out who I am,_ Hiro thinks frantically. _But I gotta get him out of here. Save Tadashi. Tadashi has to live._ In his conflict, Hiro doesn’t notice a part of the ceiling above beginning to collapse. Tadashi spots it too late, and yells at Hiro to move just as rubble falls. 

“HIRO! NO!” Tadashi yells. His brother lying on the ground, Tadashi can see that Hiro’s helmet has a large dent in it, and part of his chest plate is cracked. Hiro groans, eyes shut tight. Tadashi attempts to pull Hiro up, but his leg is stuck under some of the debris. Hiro yells in pain. _I have to get him out of here._

Tadashi digs frantically to free his brother, then pulls him up. Tadashi picks up Hiro, cradling his thin frame. _He’s surprisingly light still_ he thinks as he runs to the exit. They make it outside moments before the building blows, throwing them both down the steps. On the ground, Tadashi sees a teen Hiro and Cass running over to him, shouting his name. Looking around, he sees the adult Hiro lying on the ground, not far away. _Looks like he’s okay,_ Tadashi grins before passing out. 

\------------------------------------------------------------------------------

When Hiro wakes up, he is initially blinded by white lights and white walls. He quickly realizes that he is in the hospital, and tries to sit up. Tries. The moment he moves, pain shoots through his body. Wincing, he can feel the bandages on his head, leg, and arms. Just then, a doctor and a nurse walk into the room. When they see him awake, they both look surprised. 

“Finally awake, are you?” The doctor seems like a friendly man. “You’ve been out all night. It’s been about 12 hours since the fire at the university. How are you feeling?”

“Um,” Hiro says hesitantly, throat dry, “Everything hurts.” He attempts at smiling, but it comes off as more of a grimace. The doctor turns to the nurse, who nods and leaves the room.

“That’s no surprise. You have some pretty heavy bruising, and some minor burns. However, you would be a lot worse off if you hadn’t had that outfit of yours on. The young man who pulled you out said you were struck by a lot of debris.” This catches Hiro’s attention.

“A young man? He pulled me out? Is he okay, is he hurt?” Hiro inquires, pleading to whatever higher powers there were that Tadashi is uninjured.

“For the most part, he’s fine,” the doctor begins, watching as Hiro becomes confused. “He only has some minor burns on his back and legs, and some small scrapes and bruises.. In fact, he was already discharged.” 

Hiro lets out the breath he didn’t know he was holding as the nurse reenters the room. He watches as she administers morphine and raises the head of his bed, gradually feeling the pain subside. He looks back to the doctor, feeling less distressed.

“Now we get to the hard part.”

“What?” Hiro asks in confusion, thinking the doctor had been done. Then he remembers. _Oh shit._

“Who are you?” 

_Shit._ Hiro looks away from the doctor to his own feet. _Shit shit shit shit shit_.

“No one seems to know who you are and no one has filed a missing persons report.” 

_Shit what now._

“Oh, hello Doctor.” 

Hiro turns quickly to the door at the familiar voice. _Fuck._ Standing in the open doorway is Tadashi. 

Tadashi.

Looking at his brother, Hiro must fight to hold back tears. Tadashi has a single crutch, but doesn’t seem to be leaning on it much. He has a cut on his face. Hiro is made aware of his quickening heart rate by the monitors beside his bed.

“Ah, Mr. Hamada. Back so soon?” the doctor chuckles at his own joke. “Do you know this young man?”

Tadashi makes eye contact with Hiro for a solid second, then looks back to the doctor. 

“No sir, just wanted to check up on him and chat, since he doesn’t seem to have any visitors,” Tadashi responded, flashing a smile. 

“I see. Well, I’m just trying to figure out who our John Doe is,” the doctor says, turning back to Hiro. “So?”

“I...I don’t. I don’t remember,” Hiro makes something up, feigning an innocent and confused face. He observes as the doctor’s expression becomes strange and unreadable, different from his previously friendly demeanor.

“Alright. Then, John Doe, feel free to press the button on your bed for assistance. I need to attend to my other patients now. Mr. Hamada,” the doctor says, nodding at Tadashi as he brushes past the student. Tadashi waits a few moments for the doctor to move on to his next patient, then enters the room and closes the door. He smiles at Hiro with an air of uncertainty.

“Well then. Now that we’re alone,” Tadashi begins speaking. Hiro swallows, not wanting to make eye contact but unable to look away. He feels smaller now than he should, fearing his brother’s next words.

“We keep meeting, huh?” Tadashi asks, grin turning sly. He walks to the window and looks out. _What the hell?_ Hiro asks himself. 

“That saying, this wasn’t how I planned on us meeting again. Then again, I also wasn’t planning on having a near death experience,” Tadashi says. Then, he turns back to glance at a nervous Hiro. “I should probably stop stalling and teasing you, huh?”

“Stalling and teasing…?”

“I know who you are,” Tadashi states firmly. 

Hiro holds his breath.

“Hiro.”

If he wasn’t currently hooked up to a still-beeping heart monitor, Hiro could swear that, in this moment, his heart stops beating.

**Notes for the Chapter:**

> Okay so these chapters are still pretty short but I guess in exchange my fic updates pretty often??? *sweats nervously*


	6. Together

**Summary for the Chapter:**

> Damage is identified and the healing process begins.

“Ha, hahaha who is Hiro I don't know what you're talking about, _Sir,_ ” Hiro laughs, trying to disguise his panic and nervousness. 

“I've known you my entire life, and somehow even when you're _older_ than me I can still tell when you're lying,” Tadashi says, frowning, “Baymax identified you and showed me the footage of you in my lab in the first night.”

“Baymax? Goddamnit…” Hiro bits his lip and looks down. 

“Hiro, watch your language.” Hiro looks back up at this. He grins slyly. 

“Hasn't anyone ever told you to respect your elders, _young man?_ ” Hiro tries to say smoothly, but quivers slightly. Tadashi laughs and walks over to the bed. 

“You may be physically older, but it looks like I'm still mentally older than you,” Tadashi says, sitting down in a chair next to Hiro. Then, his face becomes more serious and he sighs. “Time travel, huh? How?” 

Hiro studies his brother's face before speaking. “Time travel. Though I'm not sure how. I don't really remember what happened for me to show up here.” Pause. “You look tired.” 

Tadashi looks surprised. “I've been going to lab in the middle of the night to see if you're there.”

“Oh.” Pause again. “I've been scoping out the Exhibition Hall.” Tadashi goes from surprised to shocked to unreadable. 

“You knew that the fire would happen,” Tadashi says it more like a fact than a question. Hiro nods. 

“And that Professor Callaghan would steal your tech.” Nod. 

“And that I ran in looking for him.” Another nod. 

“And then…?” Hiro is no longer looking at Tadashi. 

“You're really stupid, Tadashi, you know?” Hiro’s eyes blur with tears. “You ran in, and the building exploded, and…and…”

Tadashi swallows. He thinks he knows what comes next. 

“You _died._ ”

Tadashi looks at his brother, broken both inside and out. Hiro is looking down, hiding his face, but Tadashi can still see the tears as they fall onto Hiro’s hands. This is a man who has lived for the last 10 years without his big brother, the person who had promised to always protect him. The pain shows in every line of his body, and makes him look like both an old man and a young child. 

Tadashi swears to never leave his little brother’s side ever again. 

\------------------------------------------------------------------------------

“You know, we should probably get you out of here.”

Hiro looks up at Tadashi from tinkering with his damaged helmet.

“What do you mean?” 

“It’s already been 3 days since the fire. Don’t you think people are beginning to ask questions? You still don’t have an identity here,” Tadashi reminds Hiro. He’s right, as usual. Though they’ve been more or less treating him like a regular patient, some of the nurses have been giving him strange looks. 

Hiro shrugs. 

“I’m just saying, don’t you think it’s a little strange that they haven’t released you yet? Your injuries aren’t that bad that you need to stay this long.” 

“They’re probably just trying to monitor me. After all, I apparently have amnesia. They probably think I have brain damage,” Hiro reasons. He admits to himself that he’s probably gotten too comfortable in the hospital. The last two weeks were a bit of a struggle, and going back to starving on the streets doesn’t seem too attractive. 

“Hiro, I’m serious. You’re a terrible liar. I highly doubt they believe you have _amnesia_ ,” Tadashi frowns. “You need to leave the hospital, but I don’t think they’ll let you sign yourself out, much less me.”

“What are you saying?” Hiro watches as Tadashi’s frown turns into a grimace. 

“We’re breaking you out.”

“Ha! That’s your plan? Yeah, that’ll be easy,” Hiro laughs while Tadashi glares at him. 

“Alright, fine. I’ll come visit you when they put you on display for being a time traveler,” Tadashi says, shrugging. 

“Okay, okay! Give me pencil and some paper.” Tadashi pulls out the requested supplies from his school bag, and Hiro begins sketching. Several minutes later, and he has a basic map of the hospital.

“What? How did you do this? How many times have you been here?” Tadashi asks, incredulous. Hiro grins proudly.

“A lot. For work, I mean. A few years after the fire, I built another Baymax and started working to implement him into public healthcare, and I started at this hospital so I was here a lot to record data and troubleshoot any issues. He worked really well, so we started trying him out as a private, in-home caretaker too. In 10 years, Baymax is mass produced and in nearly every hospital and retirement home in the country. Actually, we’ve recently been working on bringing him overseas. Of course, I kept the one with the original chip for myself for uh, obvious reasons. You did good, Tadashi. You helped a lot of people,” Hiro explains happily, Tadashi listening, heart bursting with pride. Not only did his invention work, but his brother seemed to work tirelessly so that Baymax wouldn’t go to waste after his death. 

“So, what’s the plan?” Tadashi inquires, studying the map. 

“Hmmm. I dunno. Honestly, it’d be better to keep it simple so we don’t draw a lot of attention, but I still need to turn the cameras off so they don’t come after you,” Hiro responds, face scrunching up in thought. 

“Right. So...why not just walk out?” 

“Wait, what? Are you crazy? Wait. No. Wait, that’s...ok. I can work with this,” Hiro rambles. He stops talking and cracks his knuckles, deep in thought now. 

An hour later, and they have some kind of plan. It involves Tadashi forging a hospital ID and spending about $30 on scrubs identical to the hospital nurses’ standard ones. It also involves Tadashi proving that he’s a safe driver so that Wasabi will lend him his car. Hiro has to figure out the best route through the hospital by hacking the cameras with Tadashi’s laptop, and memorizing the daily routines of all staff. He realizes that rather than turning off specific cameras and leaving blank screens, he can instead make security see footage from similar areas of the hospital. They decide to take a wheelchair until they’re close to the emergency room, then hide in a restroom to change their hospital garb to regular clothes and wheelchair to crutches. After this, they simply walk out through the bustling ER, away to freedom. They drive away in Wasabi’s car just as the nurses discover Hiro’s empty room.

\------------------------------------------------------------------------------

Tadashi drops Hiro off a couple blocks away from SFIT, then drives the rest of the way and returns the car keys to Wasabi. He enters his lab, dumps Hiro’s backpack in the corner, and waits for the sun to set. 

Meanwhile, Hiro uses the $20 bill Tadashi gave him to grab a couple cups of coffee and pastries. He begins walking the back way to get to the labs so as not to be seen by students going home for the evening. He doesn’t notice a short asian girl popping her gum, watching him from across the street. 

When Hiro arrives at the lab, exhausted, Tadashi locks the door after him. The building is empty except for them, and the sky is showing the last rays of light against a dark backdrop. They activate Baymax and enjoy his warmth with their coffee and food. 

\------------------------------------------------------------------------------

When Tadashi finally leaves the lab, the moon is high in the sky. He rides his moped home, while Hiro sleeps soundly in the locked lab with Baymax by the window.

**Notes for the Chapter:**

> Hello again, did you miss me? Another short update for the two brothers finally coming together.


End file.
